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Old 09-08-05, 03:15 PM   #1
upthebikepunx
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straightening a bent fork?

my fork is slightly bent. i can tell the right side is like half an inch further back than the left side, and it's easy to notice the unusual shape. i'm going to san francisco tomorrow morning, and was really hoping to bring this bike with me, as it's my beater singlespeed. seeing as how it's my beater, i really don't care how professionally done this is, i just want something that i'll be able to ride on. any recommendations on how to quickly fix this?

if there isn't an amateur way to do this, how much do shops normally charge to fix this sort of thing? any places in san francisco you can recommend which will do this for cheap (and quick?)

thank you.
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Old 09-08-05, 03:19 PM   #2
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If it's not steel you're screwed.
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Old 09-08-05, 03:22 PM   #3
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it's steel.
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Old 09-08-05, 03:38 PM   #4
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if there isn't an amateur way to do this..........

The official warrenty department recomends;
1. Pull up to the corner of a concrete building.
2. Whack the S* out of the front wheel against the building until it straightens out.
3. Grin and ride away.

Disclaimer. It is your face at risk, not mine.
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Old 09-08-05, 03:59 PM   #5
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Definately a mech issue. Moved.

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Old 09-08-05, 06:16 PM   #6
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Regardless of badly it's bent, I wouldn't recomend cold settingit back to position. Also depends greatly on where on the blade the bend is. I would get a new fork. Seeing as it's your beater you could probably get away with spending very little dollars, even check the used bike shops in your area.
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Old 09-08-05, 06:52 PM   #7
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I dunno. I've fixed steel frames with a mallet and a chunk of wood. If you can find a table-mounted vise, I'd try to bend or whack it back into shape. In other words, put the crown in the vise with the blades facing up. If you've got to buy a new fork otherwise, what have you got to lose?
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Old 09-08-05, 07:36 PM   #8
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Yeah, just take the front wheel off and stick a 2x4 or whatever in there, get a helper to hold the handlebars and twist it slowly back into position. If it's just twisted, you should be able to fix it. But if both sides are bent backwards don't waste your time.
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Old 09-08-05, 08:27 PM   #9
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There are fork alignment tools for this exact problem. They are called "dropout alignment tools" or something to that effect.

Primitive, accurate and many older and more established shops with well trained mechanics use the Campagnolo versions that cost a few hundred bucks or so.


The concept is so simple and easy to duplicate that a wise and adept Sydney Muppet could do the exact same job using simple axle bolts and an old 2 dollar axle cut in half.

if, when bolted to the fork dropouts, the axles don't line up in the middle, you use crude leverage tools to bend the fork blades (while cold) until the broken halves are in perfect alignment. It's not the tools so much as the skill, knowledge, judgement and expertise required to do this this well.

this skill could be had for about 12 bucks an hour at a long time reputable shop or you could get it for for free from a common muppet like myself or from the ultimate God of Bike Forum "No Nonsense" Muppets.

However his advice comes at a price. you will have to suffer derisive comments meant to belittle you and make you feel as though you are wasting his time.

If you are ready to submit to his particular brand of froggy insults, I will call the "Master of Muppets" for you now.......

Sydney B. come in.... are you there Sydney B.. ????
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Old 09-08-05, 08:44 PM   #10
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Everytime you bend steel it weakens, I dont recommend bending the forks back at all. If its still ridable keep riding. If you bend it back chances are it will bend again and probably crack, then you are putting yourself at risk.
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Old 09-08-05, 08:55 PM   #11
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Thank you Sydney Muppet! Esp after the Muppet Greased Taper Capper.

Hey! Here's an idea, why rebend the trailing leg? Bending things forward and backwards will weaken the metal. One quick cold set in some cases will strengthen the metal! Therefore, bend the leading fork leg backwards! Then both legs (prongs?) will be equal in strength and will deflect the same amount under load! NO BUMP STEERING!!!! And the reduced trail and shorter wheel base will make for quicker steering and a dodger of Dodges you will be . And be you will, the envy of your friends
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Old 09-08-05, 09:24 PM   #12
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couple months back a coworker was jumped and someone ran over his bike. Mostly fine, except one fork leg was bent bad. We put it in a vise right below the bend, put a block of wood between the legs, and put a 12 foot long steel tube over the end and slowly worked it back into place. Barely scratched the chrome, and it's riding great...I'll post an update when it snaps off...
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Old 09-08-05, 09:28 PM   #13
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Quote:
Originally Posted by poopncow
Hey! Here's an idea, why rebend the trailing leg? Bending things forward and backwards will weaken the metal. One quick cold set in some cases will strengthen the metal! Therefore, bend the leading fork leg backwards! Then both legs (prongs?) will be equal in strength and will deflect the same amount under load! NO BUMP STEERING!!!! And the reduced trail and shorter wheel base will make for quicker steering and a dodger of Dodges you will be . And be you will, the envy of your friends
The logic is true. I love that.
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Old 09-08-05, 10:29 PM   #14
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Logic is true until you fork breaks and you do a faceplant at 40mph.
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Old 09-09-05, 06:40 PM   #15
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No reputable bike shop worth their liability insurance would allow an employee to rebend a fork. Maybe a light tweak on a fork dropout that wasn't parallel. Way better for the safety of customer and makes great financial sense for the customer to purchase a new fork, and pay for the labor to do it.

Kinda like when a customer takes a fall and crashes on the helmet. Even if there is no visible damage, why take the chance ? Just get another one for safety's sake.
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Old 09-09-05, 08:13 PM   #16
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Well half inch or less isnt a bend its a tweek. what id do personaly take the front wheel off. Place a scree driver shaft in the drop outs and pull on the side thats tweaked back. What will happen is one fork will move back alittle and the other foward a little. This will effectivel split the diffrences. Your steering will likly be noticably effected. You will get quicker response so youll want to take it around the block nice and slow a couple times to get use to it. Safty wise it should be fine. Nw any more than a half inch and id never mess with it not on a street bike. Old bmex heh ive fixxed forks with huge bends in the forks and crashed them off of jumps with no isues. Corse your talking tubes for the forks the size of a cannondales bottom tube hehe.
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Old 05-02-15, 02:59 PM   #17
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Originally Posted by Sydney_A_Muppet View Post
There are fork alignment tools for this exact problem. They are called "dropout alignment tools" or something to that effect.

Primitive, accurate and many older and more established shops with well trained mechanics use the Campagnolo versions that cost a few hundred bucks or so.


The concept is so simple and easy to duplicate that a wise and adept Sydney Muppet could do the exact same job using simple axle bolts and an old 2 dollar axle cut in half.

if, when bolted to the fork dropouts, the axles don't line up in the middle, you use crude leverage tools to bend the fork blades (while cold) until the broken halves are in perfect alignment. It's not the tools so much as the skill, knowledge, judgement and expertise required to do this this well.

this skill could be had for about 12 bucks an hour at a long time reputable shop or you could get it for for free from a common muppet like myself or from the ultimate God of Bike Forum "No Nonsense" Muppets.
I know this is an oldie but it reminded me of a BMW tool I saw a few days ago with the same pin point concept , great looking piece for frame alignment which I can only guess there is a bicycle version

BMW Motorcycle frame alignment tool | Beemers and Bits
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Old 05-02-15, 03:46 PM   #18
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I was just starting to ride lots in the 1970's (when all frames were steel). Bent forks were common. All (good) shops were experienced in realigning forks and frames. It wasn't a problem then, it shouldn't be now, especially if this is a cheaper/lower quality steel that's softer than the highest grade tubing. Can you find a mechanic or shop owner in his 60's? He'd probably know all about how to do it, be finished in less than five minutes and probably wouldn't charge too much. And since he/they could, and did do it all the time, you can also. Clamp the steerer tube firmly in place (the last time I saw this done - about five years ago, the shop had a special clamp/tool for that) and bend the fork blade. I don't remember if he just used his hands and yanked or if he used something for leverage. I have no idea as to whether this could be done with the fork in the frame - would that much bending force damage the headset? - or if the fork needs to be removed from the frame.

I notice you're in Long Beach. I'd think the LA area ought to have an "old" bike shop somewhere. Ask around until you find it, unless you try yourself. The thing I remember is that the fork needs to be clamped in place very thoroughly because of the amount of bending force you will put into it. I also remember from when I watched him do it a few years ago that he really had to bend the fork waaaayyyy beyond what you'd expect. On my fork it was only a quarter or half inch out, like yours, and if I remember right he was bending the blade and inch or two or three to reset it. I (I don't really remember how much or far any more, I just remember I was rather surprised at how far out of line he was bending it to get it to move. He was putting his whole body into it.)

Last edited by tcarl; 05-02-15 at 03:53 PM.
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Old 05-02-15, 07:17 PM   #19
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Originally Posted by Sydney_A_Muppet View Post
There are fork alignment tools for this exact problem. They are called "dropout alignment tools" or something to that effect.
Dropout alignment tools only check that the dropout faces are parallel; they do not check that the dropouts are equidistant from the frame/fork centerline, or that the dropouts are offset (raked) from the steer tube axis to the same degree. Tools like the Park FT-4 can check that:

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Old 05-02-15, 08:16 PM   #20
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Bending steel forks back into alignment is definitely a thing, and a good bike shop should be able to do it.

I had the fork on my '93 Stumpjumper bent slightly during a move, and I was able to get it realigned at a shop. It's not the same as before though, but that's becuase they didn't restore it to the original rake!
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Old 05-02-15, 09:58 PM   #21
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Certainly can tweak reasonable amounts of bend back. Have done this many times on steel forks
Also carefully inspect fork to steerer tube weld or braze junction when done.
Adjusted / aligned / tweaked some pretty bad ones over the years.
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Old 05-03-15, 12:19 AM   #22
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The OP probably doesn't care seeing as how this thread is from 10 years ago.

And hilariously enough I have the second post back then.
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Old 05-03-15, 07:03 AM   #23
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I love this place, everything from your bike will explode to drop it off the roof until it is straight, it will be fine. I had a local frame builder straighten a steel frame and fork for me, both bent, he has Marchetti and Lange tables imported from Italy and a massive fork table for the purpose, he charged $80. I have done forks with a slight bend by clamping them to a cast iron table and working very slowly to cold set.
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Old 05-03-15, 01:19 PM   #24
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10 year old post. Oh my.
Guess i will put on my glasses and look at post dates on a go fwd basis. Getting old sucks
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